This is an artefact of how the fan coil unit is controlled. The water flow is varied while the
air flow is held constant. In any NTU-effectiveness heat exchanger model, if one capacity flow rate
is small in relation to the other stream's capacity flow rate, the small flow stream will exit at the high
flow stream's temperature. If both air flow and water flow were varied simultaneously, you woul not see
this happening.
I'm not sure why the fan coil model is violating the minimum flow rate.
Fred Buhl
hata102640 wrote:
There is a similar problem to me. The cold water flow rate is too much down when the capacity of fan coil unit is controlled,so the cold water outlet temperature has risen. I set field "Minimum Cold Water Flow Rate" of object "ZoneHVAC:FourPipeFanCoil" to limit reduction of the water flow rate. However, although a minimum cold water flow rate is set, the water flow rate is still less than it. There are not too many descriptions for "Minimum Cold Water Flow Rate" in the manual. Hiroyuki --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Michael J. Witte" <mjwitte@...> wrote:I am not an expert on the coil model, but the model is explained in the Engineering Reference (p. 446, pdf p. 492). This may be impacted by the particular sizing inputs used for the coil and the plant loop. Mike On 21 Dec 2007 at 7:44, ÀE×¼ wrote:Dear EnergyPlus Support Team: I am simulating a building with fancoil as its air conditioning system.My IDF is just like the example file FanCoilAutoSize. I found that the temperature of water outlet nodes of the coils ( Objects of COIL:water:cooling) is just as high as the coils outlet air temperature.That inconsistent with the actual situation.There should be a diference in temperature between the coil water outlet nodes and the coil air outlet nodes. Is that a characteristic of Coil:water:simple,the heat trasnfer is plentitude and temperatures of the air and water outlet nodes are very close ? Thank you for your help. The primary EnergyPlus web site is found at: http://www.energyplus.gov The group web site is: http://groups.yahoo.com/group/EnergyPlus_Support/ Attachments are not allowed -- please post any files to the appropriate folder in the Files area of the Support Web Site. EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the Documentation link and press the "search" button. Yahoo! Groups Links======================================================== Michael J. Witte, GARD Analytics, Inc. EnergyPlus Testing and Support EnergyPlus-Support@...------------------------------------ The primary EnergyPlus web site is found at: http://www.energyplus.gov The group web site is: http://groups.yahoo.com/group/EnergyPlus_Support/ Attachments are not allowed -- please post any files to the appropriate folder in the Files area of the Support Web Site. EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the Documentation link and press the "search" button. Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/EnergyPlus_Support/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/EnergyPlus_Support/join (Yahoo! ID required) <*> To change settings via email: mailto:EnergyPlus_Support-digest@xxxxxxxxxxxxxxx mailto:EnergyPlus_Support-fullfeatured@xxxxxxxxxxxxxxx <*> To unsubscribe from this group, send an email to: EnergyPlus_Support-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
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